Abrasive Waterjet Cutting System For Subsea Operations

ABSTRACT

An abrasive entrainment waterjet cutting system capable of cutting objects located underwater, particularly in deep subsea environments, wherein the abrasive system is comprised of an abrasive component suspended in a hydrophobic matrix component.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on Provisional Patent Applications 61/705,420filed Sep. 25, 2012 and 61/826,078 filed May 22, 2013.

FIELD OF THE INVENTION

This invention relates to an abrasive entrainment waterjet cuttingsystem capable of cutting objects located under a body of water,particularly in deep subsea environments, wherein the abrasive materialis comprised of an abrasive component suspended in a hydrophobic matrixcomponent.

BACKGROUND OF THE INVENTION

There is a demand for underwater cutting of metals, stone, and otherhard materials for such things as mining, salvage, rescue work, offshoreplatform removal, nuclear plant service, deep ocean rock sampling,infrastructure development, petroleum exploration and development,disposal of discarded military munitions, as well as environmentalremediation. Underwater work environments are among the most difficultand dangerous operating areas for cutting objects. The development ofmanned submersibles and remotely operated vehicles (ROVs) has extendedthe maximum working depth for underwater operations, thereby magnifyingthe shortcomings of conventional underwater cutting techniques.

Problems relating to hydrostatic pressure, high liquid viscosity(compared to air), waters' high thermal and electrical conductivity, andthe lack of visibility all hamper conventional cutting technologies.Oxy-arc, oxy-fuel, oxy-hydrogen and underwater arc cutting can be usedto cut steels underwater at limited depths. Mechanical drills andcutting tools, such as circular, ring, band, wire, and abrasive saws,are also used underwater with varying degrees of success. None of thesemethods are easy to perform underwater and all have limitations thatrestrict their use. They are also generally dangerous to use aroundhazardous and explosive materials that are all too frequently found insubsea environments.

One conventional method for disposing of underwater structures is tosever them in-situ using highly skilled divers to place the necessaryexplosive charges. Unfortunately, fish and marine mammals such aswhales, dolphins, and porpoises can be killed or seriously injured up toseveral kilometers from an underwater detonation owing to the effects ofexplosive shock overpressure. Abrasive entrainment waterjets have thepotential of providing a safe and environmentally friendly alternativeto conventional underwater cutting technologies if certain obstacles canbe addressed. Such obstacles include being able to feed a substantiallysteady flow of abrasive material to the waterjet cutting head

The word “waterjet” is an ambiguous term used to broadly describeessentially any process that expels a liquid, regardless of pressure orfluid chemistry, through an orifice to form a fluid jet. Thewide-ranging term of “waterjet” is used to include everything fromlow-pressure dental hygiene equipment to high-pressure systemsincorporating abrasives that can cut through thick hardened steel. Inaddition, a further confusion is introduced as the use of the word“water” in the term “waterjet” does not limit the application's use toonly pure water as the fluid in the waterjet. In this context the word“water” can infer any fluid, any solution, and any solid material thatwill flow through an orifice under pressure, or any gas that liquefiesunder pressure, such as ammonia, to form what should more precisely betermed a “fluid” jet but by convention is defined in the trade as a“waterjet.”

Waterjets are fast, flexible, reasonably precise, and have recentlybecome relatively easy to use. They use the technology of high-pressurewater being forced through a small hole (typically called the “orifice”or “jewel”) to concentrate an extreme amount of energy through a smallarea. The restriction of the small orifice converts the high pressurewater into a high-velocity waterjet. The inlet (process) water for apure waterjet is typically pressurized between 20,000 psi (138 MPa) and150,000 psi (414 MPa). This is forced through the orifice, which istypically about 0.007″ to 0.020″ in diameter (0.18 to 0.4 mm). Theresult is a very high-velocity, very thin jet of water traveling inexcess of the speed of sound in air.

Abrasive slurry waterjet, also known as an abrasive suspension jet,typically uses a hopper filled with abrasive, water, and a slurrying orsuspension agent. This combined mixture is then pressurized and forcedthrough the orifice of the cutting head. An abrasive slurry waterjetsystem must maintain the abrasive in suspension. This is typically doneby the use of chemical additives and/or mechanical means, in order toprevent the abrasive from dropping out of suspension in the piping whichcan result in plugging and disabling of the system. Likewise, the flowof a pressurized abrasive and water slurry mix is highly erosive topiping, valves, and fittings used in the system. In addition, one ormore large pressure vessels must be used to contain a sufficient amountof abrasive slurry for cutting. Consequently, an abrasive slurrywaterjet system is typically limited in pressure to approximately 140MPa, and normally operates at pressures closer to about 70 MPa.

Abrasive entrainment waterjet uses a high velocity waterjet, formed bypressurized water passing through an orifice (jewel) of the cutting headresulting in a partial vacuum in a mixing chamber downstream of theorifice that aspirates and entrains abrasive particles that areintroduced into the mixing chamber. Although transport and delivery ofabrasive particles is typically performed by vacuum aspiration, theabrasive transport can also be performed by pneumatic conveyance, or bya fluid conveyance as an abrasive suspension, as taught in Xu, et al.,U.S. Pat. No. 6,200,203, which is incorporated herein by reference.

Abrasive entrainment waterjet technology has several advantages overabrasive slurry waterjet technology. For example, it is more reliable;it requires less maintenance; it is able to operate at internal systempressures up to about 1,000 MPa or more; it can operate in a continuousmode rather than in a batch mode; it doesn't require expensive chemicaladditives; and it is able to operate with significantly lower abrasiveconsumption.

Waterjet technology has been used underwater for cutting metals andstone. For example, waterjets were taught as being effective inunderwater mining operations. See Borkowski, P. and Borkowski, J.(2011). “Basis of High-pressure Water Jet Implementation forPoly-metallic Concretions Output from the Ocean's Bottom,” RocznikOchrony Środowiska Selected full texts, 13, ppg. 65-82. An abrasiveslurry system is taught as being capable of operating underwater as longas the internal fluid pressure is substantially higher than thesurrounding hydrostatic pressure.

While the art teaches the possibility of using waterjet technology forunderwater cutting, serious problems still exist that must be overcomebefore such technology can successfully be used commercially, especiallyin deep water.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided an abrasiveentrainment waterjet cutting system comprised of:

-   a) a source of process water for the waterjet;-   b) a waterjet pump in fluid communication with the source of process    water, which waterjet pump is capable of delivering a jet of water    at a pressure of at least 280 MPa;-   c) a stored supply of abrasive material comprised of a particulate    abrasive component at least partially suspended in a hydrophobic    matrix component;-   d) an entrainment abrasive waterjet cutting head in fluid    communication with said waterjet pump and said stored supply of    abrasive cutting material; and-   e) a means for feeding said abrasive material to said cutting head    in a controlled manner.

In a preferred embodiment of the present invention the hydrophobicmatrix component is a liquid selected from the group consisting ofaliphatic hydrocarbons having a carbon number between about 6 and about20, petroleum oils, animal oils, and plant oils.

In another preferred embodiment, the hydrophobic matrix component is agel.

In yet another preferred embodiment of the present invention thehydrophobic matrix component is a wax selected from the group consistingof plant waxes, animal waxes, and mineral waxes.

In still another preferred embodiment of the present invention the ratioof abrasive to hydrophobic matrix component is about 20:80 to about80:20.

In another preferred embodiment of the present invention the abrasivematerial is conducted to the waterjet cutting head by use of a pump thatis powered by the electrical power from an umbilical cord from a surfacevessel to an underwater remotely operated vehicle.

In still another preferred embodiment of the present invention the pumpused to conduct the abrasive material to the waterjet cutting head ispowered by the hydraulic system of a subsea remotely operated vehicle.

DETAILED DESCRIPTION OF THE INVENTION

By underwater, or under a body of water, we mean that the object to becut is found resting or part of a structure secured to the bottom of abody of water. Non-limiting examples of bodies of water include oceans,seas, bays, rivers, as well as man-made bodies of water such asreservoirs and lakes. For purposes of the present invention the objectto be cut will typically be at depths from about 30 ft (10 meters) toabout 20,000 ft (6100 meters), preferably from about 300 ft (91 metersto 1500 meters) 300 ft to about 5,000 ft.

An abrasive entrainment waterjet has a distinct disadvantage as comparedto abrasive slurry jet when used underwater because the abrasivetransport and feed system is severely hampered, if not completelydisrupted, by the hydrostatic backpressure of the surrounding waterforcing its way under pressure into the abrasive system. Water enteringthe abrasive feed system will wet the abrasive. A wet abrasive mix willbecome a relatively coarse mud that can plug the system, similar to whathappens to an abrasive slurry jet when the aqueous suspension fails.Hydrostatic backpressure increases underwater at the rate of about 9.8kPa/m (0.432 psi/ft.) of depth in freshwater and at roughly the rate of10 kPa/m (0.445 psi/ft.) of depth in seawater. Consequently, the problemis rapidly exacerbated by depth. In addition, the cold temperature ofthe surrounding seawater as depth increases can cause both moisture tobe precipitated in the abrasive feed system and the hydrostaticbackpressure to increase with an increase in likelihood of forcing waterinto the abrasive feed system.

In order to utilize the advantages of abrasive entrainment waterjettechnology over abrasive slurry waterjet technology, and to be able tosuccessfully commercially operate underwater, the following problemsmust be solved: supplying water at a pressure of at least about 280 MPato the waterjet cutting head; supplying a measured and substantiallycontinuous stream of abrasive material to the abrasive waterjet cuttinghead; and preventing plugging or jamming from the reservoir of abrasivematerial to the abrasive waterjet cutting head.

The type of waterjet cutting head used in the practice of the presentinvention will be an abrasive entrainment waterjet cutting head that isgenerally comprised of: a metal body having an outer cylindrical surfaceand a central bore substantially parallel to the cylindrical surface,with an upstream direction and a downstream direction. It will have ajewel orifice mounted in the bore in the metal body. A portion of thecentral bore will typically be downstream of the jewel forming a mixingchamber. An inclined bore for abrasive material passes from the outercylindrical surface to the central bore, preferably at an incline andjoining the central bore downstream of the jewel at the mixing chamber.There is also typically provided a nozzle wherein the waterjetcontaining the abrasive further mixes and exits.

Any type of waterjet pump can be used in the practice of the presentinvention as long as it is capable of delivering a jet of water, withentrained abrasive material, at a pressure of at least about 280 MPa toabout 1000 MPa. A referred type of waterjet pumps suitable for use inthe present invention is an intensifier pump. Waterjet intensifier pumpsare well known in the art and utilize the so-called “intensification”principle. A waterjet intensifier pump typically operates by havingpressurized hydraulic oil flow into one side of a centrally locatedhydraulic piston having double ended piston rods extending into the highpressure water cylinders at each end. The central hydraulic piston ofthe intensifier pump is typically 20 times the area of each piston rodgiving a 20:1 intensification ratio. The piston rods, in turn, form thehigh pressure water pistons. Consequently, an application of 14 MPahydraulic oil to the central hydraulic piston results in a twenty-foldintensification of pressure in the water cylinder and yields an outletwater pressure of 280 MPa. The outlet pressure of the water can becontrolled by adjusting the inlet hydraulic oil pressure. When thecentrally located hydraulic piston reaches the end of its stroke, ahydraulic valve body switches the flow of oil to the opposite side ofthe hydraulic piston and the process continues with the opposite waterpiston. The depressurized oil from the central cylinder is exhausted viathe control valves to an exhaust port connected with an oil return to anoil reservoir, which can be underwater or at the surface. High-pressurewater can be provided to the waterjet cutting head by any suitablemeans, such as by locating the waterjet pump at the surface andconducting the pressurized water to a submerged waterjet cutting head byuse of a high pressure hose. One major drawback with this method is thatusing a high-pressure hose to supply water from the surface to anabrasive entrainment waterjet cutting head underwater is a problem thatincreases with increasing depth. For example, high pressure hoses areexpensive, heavy, and have a pressure drop due to internal fluidfriction. It is known in the art that submerged hose lengths of at leastabout 2.5 times the water depth are required for efficient operations.Working at depths of 400 m (1300 ft.) would require about 1,000 m (3,300ft.) of hose with over 1.8 tons (4,000 lb.) of line tension pulling onthe hose just from its own weight.

A preferred method of supplying high pressure water is to usepressurized hydraulic oil fed by hydraulic hoses from pumps on thesurface, typically operating at pressures from about 14 MPa to 105 MPa,preferably from about 14 MPa to 35 MPa, to a waterjet intensifier pumplocated underwater and returning the resulting depressurized hydraulicoil to the surface. A hydraulic feed hose and return hose aresignificantly lighter and less expensive than high-pressure waterjethoses. The exhaust pressure alone will be sufficient to pump the oil upa return line back to the surface. As an alternative, a supplementarypump can be added to assist in pumping the oil to the surface for reuse.

High pressure hydraulic fluid can also be powered by the ROV's on-boardhydraulic system and used to power a submerged high pressure waterjetintensifier pump. Submerged operations require the use of an electricalumbilical power line from the surface to the ROV, as described by theU.S. Naval Oceans Systems Command's Technical Document 1530, dated April1989. A hydraulic power attachment can be made through a standard ROV“hot-stab” port conforming to ISO 13628-8, titled “Remotely operatedtools and interfaces on subsea production systems,” or through standardquick-disconnect fittings, such as Parker FH Series Couplings, orsimilar hydraulic connections know to those skilled in the art. Thewaterjet pump can be mounted on the ROV or mounted as an accessory unitas a separate fixture that the ROV can pick up and put down as required.A subsea hot-stab is known in the art to be a high pressure sub-seaconnector that is typically used to connect into a fluid system forintervention/emergency operations. It is typically designed to be ROVactivated. A subsea hot-stab basically comprises two parts; a valve, anda tool that connects to the valve and functions it.

In order to provide high pressures with reduced wear and increasedreliability it is preferred to demineralize the process water that isused at high pressures. By process water we mean the water that ispressurized by the waterjet pump and used for cutting. It is preferredthat the process water contain no more than about 350 parts per milliontotal dissolved solids. In comparison, seawater is typically in therange of about 35 parts per thousand of dissolved solids. Theapproximate distribution of dissolved minerals is: 55% chloride; 30.6%sodium; 7.7% sulfate; 3.7% magnesium; 1.2% calcium; and 1.1% potassiumions. In addition to the dissolved minerals, the water can containsuspended materials such as algae, plankton, and finely dispersedsolids. Process water from a surface ship can be supplied as part of anumbilical cord along with power and control cabling. It is also withinthe scope of this invention that the process water be obtained from aprocess water holding tank stored underwater and within the vicinity ofthe object to be cut. The process water can also be generated by thefiltering of seawater either at the surface or by a subsea operation.

Filtration of the seawater greatly increases the reliability of the highpressure waterjet equipment. Filtration can be provided by one or morestages of mechanical filtration using increasingly finer meshes tomechanically capture the suspended materials. These mechanical filterscan be provided with pleating, caused by alternate folding patterns, toincrease the surface area of the filter media. These mechanical filterscan also be fitted with manual or automatic backwash capabilities toallow a counter current flow pressurized water to remove surfacecontamination that can occlude the filter media, known as “blinding.” Inaddition, a secondary set of one or more containers of solid orparticulate materials with a high degree of porosity can be used toincrease the efficiency of suspended material removal by use oftorturous pathways, such as in a packed filter using crushed quartz, orby adsorption mechanisms, such as by the use of activated carbon ordiatomaceous earth.

An abrasive entrainment waterjet starts out the same as a pure waterjet,but with an abrasive entrainment waterjet, as the high pressure streamof water leaves the orifice abrasive is added to the stream at a mixingchamber. The high-velocity jet of water exiting the orifice creates avacuum that pulls abrasive from an abrasive line, which then mixes withthe jet of water in the mixing chamber of the cutting head and is jettedout of a nozzle. The jet of water accelerates the abrasive particles tospeeds fast enough to cut through very hard materials. The cuttingaction of an abrasive waterjet is two-fold. The force of the water andabrasive erodes the material, even if the jet is held stationary (whichis how an object is initially pierced). The cutting action is greatlyenhanced when the abrasive waterjet stream is moved across the intendedcutting path of the object. The ideal speed of cutting depends on avariety of factors, including the hardness of the object being cut, theshape of the object, the waterjet pressure, and the type of abrasive.Controlling the speed of the abrasive waterjet cutting head is crucialto efficient and economical cutting.

Non-limiting examples of abrasive materials that are suitable for use inthe present invention include glass, silica, alumina, silicon carbidealuminum-based materials, garnet, as well as elemental metal and metalalloy slags and grits. Preferred are garnet and aluminum-basedmaterials. It is also preferred that the abrasive particles have eithersharp edges or that they be capable of fracturing into pieces havingsharp cutting edges, such as for example, octahedron or dodecahedronshaped particles. The size of the abrasive particles may be any suitableeffective size. By effective size, is meant a size that will not plugthe cutting head and that will be effective for removing the material ofwhich the targeted object to be cut is made from (typically a metalalloy, such as steel) and which is effective for forming a substantiallyhomogeneous mixture with the fluid carrier. Useful particle sizes forthe abrasive material will range from about 3 mm to 55 microns,preferably from about 15 mm to 105 microns, and most preferably fromabout 125 microns to about 250 microns.

It is important that the abrasive material be delivered to the waterjetcutting head without jamming or plugging. In shallow water, a surfacevessel can supply dry abrasive via a hose down to the waterjet cuttinghead. A braided metal hose is recommended to prevent the hose fromcrushing under hydrostatic pressure. The aspiration of the mixingchamber in the entrainment abrasive waterjet cutting head willpreferably provide sufficient suction at depths to approximately 90 m(300 ft.). At greater depths the delivery of the abrasive materialbecomes more of a problem.

It is preferred, for the practice of the present invention, that ahydrophobic material be used as a matrix for forming a pumpable slurrywith the abrasive component. Non-limiting examples of such matrixmaterials suitable for use herein include aliphatic hydrocarbons havinga carbon number between about 6 and about 20, preferably between about10 and 14, petroleum oils, animal oils, and plant oils, preferred arehydrophobic oils, more preferred are petroleum oils. The hydrophobicmaterial is incorporated with the abrasive to form a slurry that iscapable of being mechanically injected into the abrasive waterjetcutting head at a controlled rate. This can be determined by an abrasivefeed control system using a conventional piston, gear, or peristalticpump, auger, etc. A piston pump is preferably used for conducting theabrasive slurry into the cutting head by compressing the slurry with apiston using pressure supplied by a hydraulic piston, an electricallydriven rack or threaded shaft, or a hydraulically driven rack orthreaded shaft.

The discharge rate of the piston pump can be controlled by the abrasivefeed control system by varying the duty cycle or by varying theelectricity or the hydraulic pressure applied to the piston pump motor.The ratio of abrasive to hydrophobic material will be an effectiveratio. By effective ratio we mean at a ratio that will enable theabrasive to become and stay substantially suspended in the hydrophobicmatrix material and that can be conducted, without substantial plugging,to the abrasive waterjet cutting head. It is preferred that thesuspension be a substantially homogeneous suspension. Such a ratio ofabrasive to hydrophobic matrix material, by volume, will be about 20:80to about 80:20. An excess amount of abrasive, known as a “rich” mixture,is undesirable because it will create too much pressure on the slurrydelivery system, while an excess of the hydrophobic matrix, known as a“lean” mixture, can cause the abrasive waterjet cutting head to beinefficient during cutting. The liquid hydrophobic matrix is dispersedby the high pressure jet of water along with the abrasive in the mixingchamber of the abrasive waterjet cutting head and will form asolid-liquid-liquid jet upon exiting the abrasive waterjet nozzle withthe abrasive, hydrophobic material, and water, respectively.

It is within the scope of this invention that the hydrophobic materialbe a solid or high viscosity liquid selected from greases, and waxymaterials, such as, but not limited to, paraffin wax or beeswax. Thesesolid materials incorporate the abrasive so that a flexible solid orsemi-solid strip, tube, or rod, etc., of abrasive and binder matrix(solid material) can be mechanically fed into the abrasive waterjetcutting head at a controlled rate, under the control of the abrasivefeed control system, by plastic deformation. Other non-limiting examplesof such solids suitable for use herein include plant waxes, animalwaxes, mineral jellies, mineral waxes, mineral soaps, mineral greases,and animal greases or mixtures thereof. The binder matrix is dispersedby the high pressure jet of water along with the abrasive in the mixingchamber of the abrasive waterjet cutting head and would form asolid-solid-liquid jet upon exiting the abrasive waterjet nozzle withthe abrasive, hydrophobic matrix, and water, respectively.

Hydrophobic gels can also be used for the matrix for the suspension ofthe abrasives. Gels are comprised of a solid three-dimensional networkthat spans the volume of a liquid medium and ensnares it through surfacetension effects. Non-limiting examples of hydrophobic gels suitable foruse herein include hydrophobic silica gels modified with trimethylsilyland long-chain alkyl (C6-C18) groups; hydroxypropyl beaded dextran thathas been substituted with long chain (C13-C18) alkyl ethers; andpolyethyleneglycol (PEG) end-capped with fluoroalkyl groups.

The above abrasive and hydrophobic matrix can be mechanically fed intothe abrasive waterjet cutting head at a controlled rate. This can bedone by any suitable means, such as by heating the hydrophobic matrixmaterial until it is in a plastic or liquid state, using heat,preferably by electric resistance elements or heated process fluids, forexample, from the ROV's hydraulic pump. The abrasive/hydrophobic matrixcan then be pumped to the waterjet cutting head using any suitableconventional pump, such as a piston, gear, or peristaltic pump, auger,etc. The liquefied matrix is dispersed by the high pressure jet of wateralong with the abrasive in the mixing chamber of the abrasive waterjetcutting head and forms a solid-liquid-liquid jet upon exiting theabrasive waterjet nozzle with the abrasive, liquefied hydrophobicmatrix, and water, respectively

The abrasive mix can be metered using a programmable electronic ormechanical device, known as the abrasive feed control system that willallow precise control over the quantity of abrasive mix being fed to theabrasive waterjet cutting head. In one preferred embodiment amicroprocessor-based system is used. A mechanical logic control systemlikewise can use fluidic, pneumatic, or mechanical logic processing toregulate the flow of the abrasive mix.

The abrasive feed and metering system for the abrasive mix can use anumber of types of feed systems, such as incremental piston feed systemsor increment feeders, such as belt feed, bucket feed, reciprocatingfeed, or oscillating feed, etc., powered by electrical, mechanical,hydraulic, or pneumatic means under fixed control or under the controlof the abrasive control system. Also, the abrasive feed and meteringsystem will monitor the seawater hydrostatic backpressure at theabrasive waterjet cutting head to maintain the internal pressure in theabrasive system, particularly in the abrasive reservoir, at a higherpressure, preferably about 125 Pa to 7 kPa higher, than the surroundingwater pressure by means of a differential pressure sensor.

What is claimed is:
 1. An abrasive waterjet cutting system comprised of:a) a source of process water for the waterjet; b) a waterjet pump influid communication with the source of process water, which waterjetpump is capable of delivering a jet of water at a pressure of at least280 MPa; c) a stored supply of abrasive cutting material comprised of aparticulate abrasive component at least partially suspended in ahydrophobic matrix component; d) an entrainment abrasive waterjetcutting head in fluid communication with said waterjet pump and saidstored supply of abrasive cutting material; and e) a means for feedingsaid abrasive cutting material to said cutting head in a controlledmanner.
 2. The abrasive waterjet cutting system of claim 1 wherein thehydrophobic matrix is a liquid.
 3. The abrasive waterjet cutting systemof claim 2 wherein the liquid is selected from the group consisting ofaliphatic hydrocarbons having a carbon number between about 6 and 20,aromatic hydrocarbons having a carbon number between about 6 and 20,petroleum oils, animal oils, and plant oils.
 4. The abrasive waterjetcutting system of claim 3 wherein the liquid is a petroleum oil.
 5. Theabrasive waterjet cutting system of claim 1 wherein the hydrophobicmatrix component is a semi-solid or solid material.
 6. The abrasivewaterjet cutting system of claim 5 wherein the hydrophobic matrixcomponent is selected from the group consisting of greases, waxes,gel-like materials, and soaps.
 7. The abrasive waterjet cutting systemof claim 6 wherein the hydrophobic matrix is a wax selected from plantwaxes, animal waxes, and mineral waxes.
 8. The abrasive waterjet cuttingsystem of claim 6 wherein the hydrophobic matrix is a gel.
 9. Theabrasive waterjet cutting system of claim 8 wherein the gel is selectedfrom the group consisting of silica gels, silica gels modified withtrimethylsilyl and C6-C18 alkyl groups; hydroxypropyl beaded dextran;hydroxypropyl beaded dextran substituted with C13-C18 alkyl ethers; andpolyethyleneglycol (PEG) end-capped with a fluoroalkyl group.
 10. Theabrasive waterjet cutting system of claim 1 wherein the ratio ofabrasive to hydrophobic matrix component, by volume percent, is fromabout 20:80 to 80:20.
 11. The abrasive waterjet cutting system of claim10 wherein the ratio of abrasive to hydrophobic matrix component, byvolume percent, is from about 40:60 to 60:40.
 12. The abrasive waterjetcutting system of claim 1 wherein the abrasive material is conducted tothe waterjet cutting head by use of a piston pump.
 13. The abrasivewaterjet cutting system of claim 2 wherein the piston pump is driven byelectrical power.
 14. The abrasive waterjet cutting system of claim 13wherein the electrical power is obtained from an umbilical cord from asurface vessel to a remotely operated vehicle.
 15. The abrasive waterjetcutting system of claim 14 wherein the piston pump is driven byhydraulic power.
 16. The abrasive waterjet cutting system of claim 15wherein the hydraulic power is obtained from the hydraulic system of aremotely operated vehicle.
 17. The abrasive waterjet cutting system ofclaim 11 wherein the piston pump has a microprocessor control system.18. The abrasive waterjet cutting system of claim 1 wherein the processwater has less than about 350 parts per million of dissolved solids.